A campaign spokesman said Gingrich will continue to do so when he works the rope lines after he speaks. But a "new tactic" is to make a special appeal to supporters for a more formal photo opportunity in return for a modest contribution.

R.C. Hammond, the spokesman, said some campaigns "make you travel all the way to Wall Street to pay $2,500 for a photo." And already, the more grass-roots appeal is paying off.

"Every dollar and every supporter count and our campaign is propelled forward one small donor at a time," he said.

The campaign could use the dollars. Gingrich raised just $2.6 million in February and spent $2.8 million, leaving him with $1.54 million in cash and $1.55 million in debt.

His campaign is benefiting from continued infusions of money into a "super PAC" backing his campaign, mostly from casino magnate Sheldon Adelson and his family. The Adelsons gave $5.5 million to Winning Our Future in February, bringing their total to $16.5 million.

Gingrich acknowledged his tight finances during a stop in Annapolis, Md., Tuesday, but maintained he'll have enough to stay in the race until the national convention in Tampa, Fla., in August.

"Clearly we're going to have to go on a fairly tight budget to get from here to Tampa," he said, according to our colleagues at the Baltimore Sun.

Gingrich also found time for a stop at the Salisbury Zoo in Salisbury, Md. Admission there is free.